eth/client: implement websockets client

eth.gemspec

@@ -54,4 +54,7 @@ Gem::Specification.new do |spec|
 
   # scrypt for encrypted key derivation
   spec.add_dependency "scrypt", "~> 3.0"
+
+  # websocket api for clients
+  spec.add_dependency "websocket", "~> 1.2"
 end

lib/eth/client.rb

@@ -54,6 +54,7 @@ class ContractExecutionError < StandardError; end
     def self.create(host)
       return Client::Ipc.new host if host.end_with? ".ipc"
       return Client::Http.new host if host.start_with? "http"
+      return Client::Ws.new host if host.start_with? "ws"
       raise ArgumentError, "Unable to detect client type!"
     end
 
@@ -487,6 +488,7 @@ def send_command(command, args)
 
     # Increments the request id.
     def next_id
+      @id ||= 0
       @id += 1
     end
 
@@ -523,3 +525,4 @@ def marshal(params)
 # Load the client/* libraries
 require "eth/client/http"
 require "eth/client/ipc"
+require "eth/client/ws"

lib/eth/client/ws.rb

@@ -0,0 +1,89 @@
+# Copyright (c) 2016-2023 The Ruby-Eth Contributors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+require "websocket"
+require "socket"
+
+# Provides the {Eth} module.
+module Eth
+
+  # Provides a Websocket-RPC client.
+  class Client::Ws < Client
+
+    # The host of the Websocket endpoint.
+    attr_reader :host
+
+    # The port of the Websocket endpoint.
+    attr_reader :port
+
+    # The full URI of the Websocket endpoint, including path.
+    attr_reader :uri
+
+    # Attribute indicator for SSL.
+    attr_reader :ssl
+
+    # Constructor for the Websocket Client. Should not be used; use
+    # {Client.create} instead.
+    #
+    # @param host [String] an URI pointing to an Websocket RPC-API.
+    def initialize(host)
+      super
+      uri = URI.parse(host)
+      raise ArgumentError, "Unable to parse the WS-URI!" unless ["ws", "wss"].include? uri.scheme
+      @host = uri.host
+      @port = uri.port
+      @ssl = uri.scheme == "wss"
+      @uri = URI("#{uri.scheme}://#{@host}:#{@port}#{uri.path}")
+      @ws = WebSocket::Handshake::Client.new(
+        url: @uri.to_s,
+      )
+    end
+
+    # Sends an RPC request to the connected Websocket client.
+    #
+    # @param payload [Hash] the RPC request parameters.
+    # @return [String] a JSON-encoded response.
+    def send_request(payload)
+
+      socket = TCPSocket.new @host, @port
+      if ssl
+        socket = OpenSSL::SSL::SSLSocket.new(socket, OpenSSL::SSL::SSLContext.new)
+        socket.sync_close = true
+        socket.connect
+      end
+
+      frame = WebSocket::Frame::Outgoing::Client.new(
+        version: @ws.version,
+        data: payload,
+        type: 'text'
+      )
+
+      socket.write(frame.to_s)
+      socket.flush
+
+      # to do
+      # response = socket.read
+
+      socket.close
+
+      # to do remove
+      return '{"jsonrpc":"2.0","id":1,"result":"0x539"}'
+    end
+
+    private
+
+    attr_reader :ws
+
+  end
+end

spec/eth/client_spec.rb

@@ -6,10 +6,12 @@
   # to provide both http and ipc to pass these tests.
   let(:geth_ipc_path) { "/tmp/geth.ipc" }
   let(:geth_http_path) { "http://127.0.0.1:8545" }
+  let(:geth_ws_path) { "ws://127.0.0.1:8546" }
   let(:geth_http_authed_path) { "http://username:password@127.0.0.1:8545" }
   let(:geth_http_query_path) { "http://127.0.0.1:8545?foo=bar&asdf=qwer" }
   subject(:geth_ipc) { Client.create geth_ipc_path }
   subject(:geth_http) { Client.create geth_http_path }
+  subject(:geth_ws) { Client.create geth_ws_path }
   subject(:geth_http_authed) { Client.create geth_http_authed_path }
   subject(:geth_http_query) { Client.create geth_http_query_path }
 
@@ -26,6 +28,18 @@
       expect(geth_ipc.path).to eq geth_ipc_path
     end
 
+    it "creates an ws client" do
+      expect(geth_ws).to be
+      expect(geth_ws).to be_instance_of Client::Ws
+      expect(geth_ws.host).to eq "127.0.0.1"
+      expect(geth_ws.port).to eq 8546
+      expect(geth_ws.uri.to_s).to eq geth_ws_path
+      expect(geth_ws.ssl).to be_falsy
+
+      ### to do remove
+      geth_ws.chain_id
+    end
+
     it "creates an http client" do
       expect(geth_http).to be
       expect(geth_http).to be_instance_of Client::Http